Traceable Ring Signatures with Post-quantum Security

Abstract

Traceable ring signature (TRS), a variant of ring signature, allows a signer to sign a message anonymously labeled with a tag on behalf of a group of users, but may reveal the signer’s identity if he creates two signatures with the same tag. TRS provides accountable anonymity for users, and serves as an important role in e-voting systems and e-coupon services. However, current TRS schemes are built on hard problems in number theory that cannot resist quantum attackers. To address this issue, first, we propose a general framework of TRS, by using a non-interactive zero-knowledge proof of knowledge, a collision-resistant hash function, and a pseudorandom function with some additional properties. Then, we construct an efficient TRS scheme in the quantum random oracle model, by instantiating the framework with appropriate lattice-based building blocks. Moreover, the signature size of the lattice-based TRS is logarithmic in the ring size.